This invention relates to a heat exchanger of the regenerative type wherein outgoing hot gases pass along a plurality of gas flow passages within a matrix, the heat stored therein being utilised to heat in-coming cool gases.
One regenerative heat exchanger of this type is that known as a rotary regenerator wherein the matrix is in the overall form of a disc mounted for rotation in such manner that each of its end faces passes continuously between hot and cold gas flow passages. At the actual end faces of the matrix there are provided sealing means to maintain separate on the one end face, for example, incoming hot gas and outgoing heated air, and on the opposed end face, incoming cold air and outgoing cooled waste gas.
One application of such a rotary regenerative form of heat exchanger has been in the recovery of heat from waste gases for use in air heating duties. Known forms of such heat exchangers having such an application include a disc matrix comprising a plurality of metallic or ceramic heat storage elements carried in metallic cages or baskets which totally enclose the elements and onto which the gas and air interface seals locate and operate. In such a construction the maximum operating temperature of the heat exchanger depends upon the structural integrity of the metallic cage at high gas temperatures and also upon the ability of the sealing system to cope with thermal distortions of the cage. In practice, cost considerations have limited the choice of metals for cage fabrication, and with existing plant the limit for hot gas temperature has been of the order of 1000.degree. C.
In our co-pending British patent application 47199/74 filed Oct. 31, 1974, there is described a sealing system capable of obviating some of the sealing problem which can occur during distortion of the metallic cage and/or the metallic or ceramic heat storage elements.